The objective of the proposed research is to obtain an improved understanding of the nature of the changes in driving performance attributable to alcohol. Studies will be made of vehicle steering in driving tasks on an off-highway test track and by use of a closed-loop driving simulator, to evaluate the effects of alcohol, stress, additional information processing using a subsidiary task, and incentives. These variables will be studied because research indicates that they affect task performance under alcohol. Car-following performance will also be examined. This will be done using the simulator to study both normal car-following and the behavior of drivers in the avoidance of potential rear-end accidents by modeling actual crash situations in the simulator. Since two studies have now been completed to indicate that important changes in the visual behavior of drivers in daytime driving conditions occur attributable to the effects of alcohol, it is proposed to conduct a second experiment in which eye fixations of drivers are measured in night driving on an off-highway test track facility. This will allow comparisons to be made of the effects of alcohol upon visual information acquisition for vehicle control purposes in the reduced illumination conditions found in night driving and those in daytime. Performance on these tasks will be studied using social drinker subjects, including young drivers who have relatively little driving and drinking experience. This will allow inferences to be made of the relative effects of alcohol on persons who are experienced or inexperienced in both driving and drinking.